Shareholders in Germany's Siemens called for a protest vote against the group's managing and supervisory boards over a corruption scandal at the firm.

It came at the annual general meeting of Europe's largest engineering firm.

The AGM came a day after the firm was hit with the European Commission's biggest ever fine - 396m euros (£260m; $513m) for cartel activity.

Shareholders say the firm informed them too late, underestimated the affair and did not take prompt action.

The firm is also been investigated over allegations of embezzlement.

And management have also been criticised after its former mobile phone unit BenQ went into insolvency.

Siemens said its net profit fell by 16% to 788 million euros in the three months to the end of December 2006, in part because of the cartel fine.

'Cheats'

Siemens was one of 11 firms fined by the EU for carving up the market in electrical generation equipment - but was given by far the largest of the fines, which totalled 750m euros.

Regulators found that the companies rigged bids for contracts and fixed prices in the market for gas-insulated switchgear - equipment is used to control the flow of energy in electricity grids

They also divided up projects among themselves and shared sensitive information, the commission said.

"The commission has put an end to a cartel which has cheated public utility companies and consumers for more than 16 years," EU Competition Commissioner Neelie Kroes said.

"It has once more shown that it will not tolerate cartels in Europe and the damage that they do in any area of business."

Taskforce

The finding adds to the woes at the firm, which in November had its offices investigating allegations of embezzlement and corruption.

German media said the probe had been triggered by claims that Siemens staff had paid bribes to win contracts.

About 30 business premises and private homes were searched as part of the investigation. Siemens said it was cooperating and that the raid "cast a shadow" over the company.

The conglomerate has also set up a taskforce aimed at fighting corruption. Meanwhile many blame Siemens for the plight of its former mobile phone unit, which it sold to Taiwan's BenQ and went into insolvency in September, threatening 3,000 jobs.

There are also concerns among some shareholders and employees that management has proposed to give itself a 30% pay rise.